Hills made of ice and rivers carved by liquid methane mark the surface of Saturn鈥檚 giant moon, reveal data from the Huygens probe. 快猫短视频s are now beginning to get a coherent picture of Titan after the probe landed there on 14 January. The coldest world that humanity has ever explored bears a strange resemblance to Earth, boasting hills, river systems, and mud flats.
The probe survived an unexpectedly bumpy ride through the atmosphere of Titan but enjoyed a soft landing, settling several centimetres into the surface, Huygens鈥� scientists revealed at the European Space Agency鈥檚 headquarters in Paris on Friday.
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They have now analysed many of the images returned by Huygens鈥� cameras. In one small region just 1 kilometre across, the camera team have combined images to get a 3D view of Titan鈥檚 ice hills. 鈥淲e see a ridge system with a peak 100 metres tall,鈥� says Marty Tomasko of the University of Arizona, US, and head of the Huygens imaging team. There is even a hint of how the hills are built: 鈥淚n another region we see a white streaky pattern, evidence of water ice being extruded by the surface.鈥�
Dark channels cutting across this area are now clearly revealed as drainage systems. 鈥淲e see a river system that flows down into a delta. There are also short, stubby channels indicative of springs flowing out of the hillsides,鈥� says Tomasko.
Flammable world
快猫短视频s speculated long ago that some kind of hydrocarbon liquids might flow on Titan. 鈥淲e鈥檝e learned that our speculation was really pretty good,鈥� says Toby Owen, of the University of Hawaii, an expert on Titan鈥檚 atmosphere.
They now know that the fluid that carved the moon鈥檚 rivers and channels is methane. Huygens鈥� chemical analyser saw that methane gas becomes more concentrated lower in Titan鈥檚 atmosphere, just like water vapour on Earth.
After landing, Huygens鈥� gas chromatograph and mass spectrometer instrument saw methane concentrations jump by 30%. The gas was probably evaporated from the muddy soil by heat from the European Space Agency鈥檚 probe. 鈥淚t means there鈥檚 methane near the surface,鈥� says Owen, 鈥淭itan is a flammable world.鈥� But all the oxygen is trapped in ice. 鈥淭hat鈥檚 a good thing, or Titan would have exploded a long time ago.鈥�
While there are many signs of liquid on Titan, there is none currently visible to Huygens. 鈥淭itan may be typical of arid regions of Earth like Arizona, where riverbeds are dry most of the time,鈥� says Tomasko. 鈥淧erhaps there鈥檚 a wet season once a year. We just don鈥檛 know.鈥�
Exotic materials
The mud may be a mixture of ice, sand, methane and complex organic molecules that form in the upper atmosphere. 鈥淭his smog falls out of the atmosphere and settles on everything. Then methane rain comes, washes it off the ice ridges and into rivers, then out into a broad plain where the rain settles into the ground and dries up. We are seeing evidence of Earth-like processes but with very exotic materials,鈥� says Tomasko.
There are plenty of mysteries still to unravel. Methane is constantly being destroyed and turned into a complex chemical smog, so there must be some methane source inside Titan to replenish the atmosphere. And certain gases, including argon, are inexplicably absent from Titan鈥檚 atmosphere, which may be a clue to how the moon formed.
However, Huygens has seen only one small patch of the surface 鈥� which might turn out to be unusual 鈥� it might even have come down in a desert. 鈥淭his is one single place on an interesting and varied world,鈥� says Owen.
Jean-Pierre Lebreton, the Huygens mission manager hopes that the probe will inspire a new mission to Titan: 鈥淭he next capability to bring to Titan is mobility. We can now seriously dream of sending rovers to its surface. Or flying machines, or balloons to float around the moon. We just need the money.鈥�
